Building on work already accomplished, we shall continue a major effort to complete the total synthesis of the antibiotic and tumor inhibitor pentalenolactone. In this activity, we should pass through analog structures, not readily available from the natural product itself, whose biological activity will be of considerable interest. Having completed the first total synthesis of prephenic acid, as its sodium and barium salts, we hope to prepare interesting analogs for the purpose of testing enzymic recognition and possible antibiotic properties. We hope to begin programs aimed at the synthesis of pre-tyrosine and griseofulvin.